ARM errata 430973 on multi platform kernels (was: OMAP3-N900: Add microphone bias voltages)

[Pali Rohár]

On Sunday 05 April 2015 15:00:45 Sebastian Reichel wrote:
> On Fri, Apr 03, 2015 at 02:21:48PM -0500, Robert Nelson wrote:
> > >> And yes, for armhf userland one gets random oopses at
> > >> least on the Nokia N900. AFAIK this is not true for all
> > >> ARMv7 processors (especially non omaps), though.
> > >> 
> > >> > http://www.spinics.net/lists/linux-omap/msg108511.html
> > >> > 
> > >> > See also 5c86c5339c56 ("ARM: omap2plus_defconfig:
> > >> > Enable ARM erratum 430973 for omap3").
> > >> 
> > >> For me the random oopses occur without this config flag
> > >> and are fixed by it. The workaround is not very suitable
> > >> for multi platform kernels, though, since its enabled
> > >> also for unaffected platforms.
> > >> 
> > >> As far as I can see the CONFIG_ARM_ERRATA_430973 flag is
> > >> checked in proc-v7.S and in proc-v7-2level.S. I think
> > >> the first file is irrelevant, since it can be fixed
> > >> later (see workaround in nokia_n900_legacy_init in
> > >> pdata-quirks.c).
> > > 
> > > Yes so it seems, and the bootloaders should really set it.
> > > It's also disabled for multiplatform builds.
> > 
> > These are now done in u-boot as of: v2015.04-rc4
> > 
> > http://git.denx.de/?p=u-boot.git;a=commit;h=c6f90e1418a84fe5
> > fa463b38403bd1845cb6a59c
> 
> Seems like "include/configs/nokia_rx51.h" has been forgotten.
> Note, that the kernel must still be able to enable the bit
> itself (in case NOLO is used without u-boot).
> 
> -- Sebastian

You must not expect that bootloader set something. Nokia N900 has 
closed and signed bootloader which cannot be easily replaced and 
or fixed.

For N900 there is U-Boot but it does not support lot of things 
(load kernel via usb or serial) so for developers it is better to 
use original Nokia bootloader.

-- 
Pali Rohár
pali.rohar at gmail.com
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